Year: 2024
Type: article
Abstract: ABSTRACT The radial velocity (RV) method of exoplanet detection requires mitigation of nuisance signals arising from stellar activity. Using analytic cool and facular spot models, we explore the use of central line moments (CLMs) for recovering and monitoring rotation induced RV variability. Different spot distribution patterns, photosphere-spot contrast ratios, and the presence or absence of the convective blueshift lead to differences in CLM signals between M and G dwarfs. Harmonics of the rotation period are often recovered with the highest power in standard periodogram analyses. By contrast, we show the true stellar rotation may be more reliably recovered with string length minimization. For solar minimum activity levels, recovery of the stellar rotation signal from CLMs is found to require unfeasibly high signal-to-noise observations. The stellar rotation period can be recovered at solar maximum activity levels from CLMs for reasonable cross-correlation function (CCF) signal-to-noise ratios >1000–5000. The CLMs can be used to recover and monitor stellar activity through their mutual correlations and correlations with RV and bisector inverse span. The skewness of a CCF, a measure of asymmetry, is described by the third CLM, $M_3$. Our noise-free simulations indicate the linear RV versus $M_3$ correlation is up to 10 per cent higher than the RV versus bisector inverse span correlation. We find a corresponding ∼5 per cent increase in linear correlation for CARMENES observations of the M star, AU Mic. We also assess the effectiveness of the time derivative of the second CLM, $M_2$, for monitoring stellar activity.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,012
Funders: Albert Ellis Institute, Ministerio de Ciencia, Innovación y Universidades, Centres de Recerca de Catalunya, Deutsche Forschungsgemeinschaft, Generalitat de Catalunya, Ministerio de Ciencia e Innovación, Science and Technology Facilities Council, European Regional Development Fund, Agencia Estatal de Investigación
Awards: G1105844351, G1175115578, G1353885700, G1622782223, G2064873908, G2262748287, Astronomy at The Open University 2023-2026 (Consolidated Grant), G2499501003, G2756433129, G2945112853, G3005324705, G300979063, G302750986, G34346518, G344414887, G3452655474, G3480869486, G3487714248, G3715634343, G3772858555, G390761925, G410571670, G425668148, G427883980, G451917667, G4655338613, G4794081040, G491712853, G5080475149, G5180915604, G5404395142, G5539308778, G5783525505, G5967599077, G6085756319, G617610489, G624877701, G6445425049, G6513613686, G6656126374, G6731524417, G69051668, G7084143925, G764577550, G7805626310, G7863371703, G8497050386, G8637226926, Astronomy at the Open University 2020-2023, G929308097, G99296377
OpenAlex ID: W4402543523